Light Relations in a Plum Orchard Trellised Horizontally in Comparison with Standard, Central Leader Training

Plum trees of ‘Elena’, designed for mechanical harvesting with a straddle self-propelled harvester, were planted in 2008 in the experimental orchard at Dąbrowice at a distance of 4 × 1.5 and 2.0 m. The trees were trained to a central leader to a height of 2.7 m and 1.5 or 2.0 m spread. Plum trees designed for mechanical harvesting with a small tractor-driven harvester were spaced at 4 × 1.0 or 1.5 m and were trellised horizontally on wires stretched along rows 0.8 m above the ground. Fruits were harvested in 2012–2015. The cumulative yield from the trellised trees was only half of that from the trees trained to a central leader, whereas the fruit load index (weight of fruits per m3 canopy) was the highest at 4 × 1.0 m). To explain this phenomenon, studies were conducted in 2015 on light relations in the two training systems. The studies revealed that light transmission has different patterns in the two training systems, but the level of light interception was nearly similar. Light distribution was more beneficial for photosynthesis in the central leader trees. The trees trained to a horizontal canopy had poor illumination at the canopy base. The main reason of low productivity of the horizontal canopy was low canopy volume

Preliminary Valuation of “Y” and “V”-Trellised Canopies for Mechanical Harvesting of Plums, Sweet Cherries and Sour Cherries for the Fresh Market

Plums, sweet cherry, and sour cherry trees were spaced 4.5 m × 1.5 m to be trained to “Y” and “V”-trellising systems for mechanical harvesting, with a canopy contact harvester, attending to obtain fruits meeting the requirements of the fresh fruit market. The applied trellising systems were compared with the standard central leader system at the same spacing. The most of trellised trees grew less vigorously than the standard trees, and after 3 years of training, the trees were suitable for mechanical harvesting with the harvester designed at the Research Institute of Horticulture in Skierniewice. The trellised trees were able to set as many fruitlets as those grown in the form of central leader and gave a comparable yield, but differences between cultivars were significant. Light interception in the third year after planting was lower for trees of sour cherry and plum growing in the “Y”-20° and “V” in comparison to the trees with central leader. Illumination of trellised canopies at the level of 0.7 and 1.5 m was the most favorable in “V” system when compared to control and “Y” training systems. Cost of construction for the trellising systems of stone fruits calculated per 1 ha was two times higher when compared with the standard system

The Response of Weeds and Apple Trees to Beneficial Soil Microorganisms and Mineral Fertilizers Applied in Orchards

The effect of beneficial soil fungi, bacteria and mineral fertilizers containing nitrogen, phosphorus and potassium on the level and species composition of weed infestation, uptake of macronutrients by weeds and the nutritional status of ‘Sampion’ apple trees with nitrogen (N), phosphorus (P), potassium (K), magnesium (Mg) and calcium (Ca) was assessed in three-year studies. In the field experiment, the effect of thirteen treatments was investigated, where fungal or bacterial inocula and mineral fertilizers at a standard dose and a dose reduced by 40% were applied individually or together. The fungal inoculum contained two species: Aspergillus niger and Purpureocillium lilacinum. The bacterial consortium consisted of three Bacillus strains: Bacillus sp., Bacillus amyloliquefaciens and Paenibacillus polymyxa. The weight of weeds and the uptake of macronutrients by weeds in the apple orchard increased significantly more after the application of mineral fertilization than after the application of beneficial organisms. The increased uptake of macronutrients by weeds did not significantly change the mineral nutritional status of apple trees expressed as the content of N, P, K Mg and Ca in apple leaves. After the use of NPK mineral fertilization, also with the addition of beneficial organisms, the uptake of N by both weeds and apple trees increased. P and K were more efficiently absorbed by weeds and they achieved greater benefits from fertilization with these two macroelements than trees

Suitability Of Plum And Prune Cultivars, Grown In A High Density Planting System, For Mechanical Harvesting With A Canopy Contact, Straddle Harvester

The relation of hand-harvesting cost in plum and prune production to the total costs amounts to 25-40%. Mechanical harvesting makes it possible to cut drastically both the harvesting and total costs. To test the suitability of plum and prune species to be mechanically harvested, an experimental grove (area 0.8 ha) was established in 2008. Three plum cultivars and one prune cultivar grafted on semi-dwarf and vigorous rootstocks were planted at high density (1250; 1666; 2500 trees·ha−1). During the span of full yielding (2012-2014), fruits were harvested mechanically with a canopy contact, straddle harvester in continuous motion, designed at the Institute of Horticulture in Skierniewice, to harvest tart cherry, and later adapted to harvesting plums and prunes. Trees grafted on semi-dwarf rootstock (‘Wangenheim Prune’) appeared to be more suitable for mechanical harvesting than strong-growing trees grafted on Prunus cerasifera clone ‘Myrobalan’. Cumulative yield per ha (years 2012-2014) was the highest at the highest planting density. Trees grafted on the semi-dwarf rootstock had a higher productivity index than trees grafted on the vigorous rootstock. There was no significant difference in fruit quality related to planting distance. Mechanical harvesting was nearly 40 times more efficient than hand picking. The efficiency of mechanical harvest was from 85% to 90%. Over 5% of fruits were lost on the ground and from 1 to 5% of fruits were left on the tree. Up to 18% of the plums and no more than 10% of the prunes harvested mechanically showed some damage. They can be fully acceptable for processing, for up to 10 days, providing the potential deterioration processes are inhibited by cold storage. The large-fruited cultivars seem to be more susceptible to bruising than the small-fruited ones. For the latter, the share of marketable quality fruits within the mechanically harvested crop amounted to about 80%, which could be a good prognostic justifying further trials on the prune harvester

Effect of beneficial microorganisms on the vegetative growth, yielding and nutritional status of "šampion" apple trees

The effects of bacterial and fungal inocula on the growth, yielding, and nutritional status of apple trees was evaluated in 3-years experiment (2018 - 2020). The experiment included the following treatments: (i) control (unfertilized soil), (ii) no fertilization + soil application of fungi, (iii) no fertilization + soil application of bacteria. The mixture of beneficial fungi contained two species: Aspergillus niger and Purpureocillium lilacinum. The mixture of beneficial bacteria contained three strains of Bacillus (Bacillus sp., Bacillus amyloliquefaciens and Paenibacillus polymyxa). The application of beneficial microorganisms (especially bacterial strains) to the soil (without additional mineral fertilization) enhanced the growth of the apple trees. In the third year of the study (2020), the trees grown in the plots inoculated with bacteria bloomed the most intensively. Plant nutritional status (expressed as concentrations of elements in leaves) was not affected by the application of the bacterial strains or filamentous fungi. The stronger growth of trees in the plots where the bacteria were used was likely related not so much to the nutritional status of the trees, but to the mitigation of the influence of the negative factors that cause the replant disease